Remote control systems for control of gates or garage door operators are known in the art. These systems ordinarily employ a security code. In a typical system each remote portable unit and each base unit has an operator specified security code. Each portable unit is capable of transmitting a signal encoded with the particular security code set therein. Likewise, each base unit is responsive only to signals including a security code corresponding to the security code set in that base unit. Thus a particular portable unit and base unit which are to be used together must have the same security code. This presence of a security code permits more than one remote control system employing the same radio frequency to be used in the same neighborhood. In particular, it is possible to permit a relatively large number of security codes thereby greatly decreasing the likelihood that another portable unit by the same manufacturer would unintentionally operate a particular base unit. In addition, this reduces the possibility of unauthorized entry by persons having knowledge of a particular manufacturer's technical characteristics.
The security code in both the portable unit and in the base unit must be match in order to support these security goals. It is known in the prior art to construct both the portable unit and the base unit having security codes which are operator selectable or operator alterable. In a typical remote control system of this type both the portable unit and the base unit would have their security codes set by a bank of switches. Such switches are typically embodied in miniature form in a dual in line package which is mounted on a circuit board in both the portable unit and in the base unit. A particular code is specified digitally depending upon the switch state of these switches. Selection of a particular security code involves the operator switching the bank of switches in both the portable unit and in the base unit to the same pattern, thereby specifying the same security code in each unit. Such remote control systems are typically sold in packages including one or more portable units and a single base unit. In order for the system to be initially operable upon installation, it is typical for each of the portable units and for the base unit to be set to a single factory preset code when first delivered to the purchaser. In this manner the system can be thoroughly tested to determine that it operates properly prior to the user selecting the particular security code to be used in his installation.
This manner of specifying the security code is not without its problems. Firstly, the typical dual in line switch banks employed are very small and difficult to manipulate. Typically it requires the use of some sort of stylus, such as a pencil point, in order to manipulate the switches because an individual finger is too large to select a single switch. This is thus a difficult and tedious procedure. In particular, because it is necessary to have the security codes in the portable units exactly match the security code in the base unit, errors in specifying the security code in the various units are likely to occur. This could occur due to the relatively small nature of the switches leading to confusion in recognition of exactly the code employed in each unit. In addition, it is possible to have one unit oriented incorrectly and therefore have the exact opposite code in the two units, even though the switches appear visually to have the same position.
This difficulty in selecting the particular security code in accordance with this typical prior art system leads to an additional problem. It has been found that many units returned from the field for repair have not been changed from the original factory preset code as they were delivered to the user. A base unit having such a security code is thus responsive to any newly purchased remote unit, virtually obviating the advantage of the security code system. It is believed that the difficulty in changing the security code is the reason why a significant portion of the units employed in the field are not changed from the factory preset code.
A further security difficulty results from the employment of this system for setting the security code. Because the security code can be visually read from the position of the switch bank, such a code is susceptible to unauthorized reading. Any person who has momentary access to one of the portable units can view this switch bank and determine the security code for that portable unit and the corresponding base unit. Because the typical use of such remote control systems is for garage door operators, the portable units are ordinarily stored in an automobile. Thus, anyone have momentary access to the automobile may be able to determine the particular security code of the garage where that automobile is ordinarily stored. Thus, for example, unscrupulous automobile repair facilities or service stations may use this method for entry for theft.
It is therefore a need in the art for a remote control operator system which overcomes these disadvantages. Such a system should have a relatively easy manner for setting the security code in both the base and in the portable units. In addition, such a remote control system should have a portable unit whose security code cannot be easily determined.